Hydraulic control mechanism



Jan. 4, 1944. P. N. OBERHOLTZER 2,338,350

` HYDRAULIC VCONTROL MECHANISM Filed Deo. 24, 1940 2 Sheets-Sheet lPatented Jan. 4, 1944 HYDRAULIC coN'raoL MEcnANlsM Paul N.. Oberholtzer,Oreland, Pa., assigner to American Engineering Company, Philadelphia,

Pal, a corporation o! Pennsylvania Appucationneceiber 24, 1940, serialNo. 371,495

2 c1aims.- (ci, so-52) This invention relates to hydraulic controlmechanisms having particular reference to hydraulic presses or extrudingapparatus.

One object of the present invention is to provide in a. device of theclass described certain automatic' connections which enable operation ofa platen in a predetermined sequential order.

A more speciiic object is to provide a generally improved hydrauliccontrol mechanism which may be so adjusted as to cause the press platento move toward the worky at a relatively high speed, to materiallyreduce the speed of the platen and increase the system pressure as itengages the work, and to cause said platen to travel at an increasedspeed when a higher predetermined pressure is attained.`

A further object is to provide a hydraulic control mechanism which issimple in construction and eicient in operation. l

Other and Vfurther objects will rbecome apparent as the descriptionofthe invention progresses. f

Of the drawings: t

Fig. 1 is a general assembly v matic in part, of the entire controlmechanism comprising the present invention.

Fig. 2 is an end view, partly in section, of one of the pumps includedin thehydraulic system showing certain of the control elementsassociated therewith.

Fig. 3 is a sectional view of one of the control valves in the hydrauliccircuit, and.

Fig. 4 is a sectional view taken substantially along line 4, 4 of Fig.2.

Referring to the drawings, the numeral I-indicates the entire hydrauliccontrol which, in the Apresent instance, includes a high pressure pump2, and a low pressure pump 3 for actuating the plunger or platen 4 of anextruding apparatus 5. Pumps 2 and 3 are simultaneously actuated .by anysuitable electricmotor 6. Pumps 2 and 3, and electric motor 6 aremounted upon a makeup tank 1 from which fluid is system view, diagramldrawn into pump 2 through a pipe 8, and into l nects pipe I0 to a reliefvalve I3 which in turn is connected to makeup tank 1 by a pipe I4.

Relief valve I3 is of the usual type comprising a casing I5 having aplunger I6 provided therein.

A spring |1 extends between plunger |6 and a spring seat I6, the latterofjwhich may be r-.ad'

spring I1 by a justed to vary the pressure of thumb screw I9. Y

Pipe I0 is also connected tothe central port-. 2|| of an operating valve2| by a pipe 22. Oper ating vaivevZI comprises a central chamber 23,`having a valve member 24 provided therein. ;As` shown in Fig. l, valvemember 24 is provided with 3 spaced valve heads 24a, 24b and 24C. Thestem 21 of valve member 24 is pivotally connected to an operating lever28 pivoted at 29 and movable from its neutral position shown in fulllinesin Fig. 1 to positions A and B shown in broken lines. i

Valve 2| also has provided therein apassage 36 which is connected tocentral chamber 23 by communicating passagesv 3| and 32. When lever 28is in its neutral position shown in -ful1 lines in Fig.

1, passages 3| and 32 are-closed by valve headsvr i' 24 and 24respectively, thereby preventing thel f passage of viiuid into passagefrom chamber y23.

A port communicating with passage 30- has connected thereto one end ofthe pipe 34, the

other end being connected to apipe which con-y t nects thepilot valve 36to makeup tank 1as will; i

appear more fully hereinafter. A third port 31 of valve 2| disposedbetween valveheads 24a and` 24b has connected thereto one end of `a pipey36,

the other end of which is connected to a .pipe 39 leading, fromacheckvvalve 40vto certain controls duce a predetermined pressure in thesystem to` ensure operation of a 4-way valve 43.

Valve 42 comprises a casing 44v having a plunger 45 mounted thereinAspring 46 extends between plunger 4 5 and a spring seat 41, the latterbeing adjustable by a.y thumb screw 48, to vary the pressure of saidspring 46.

Pipe 39 is also connected to the port 50 of pilot valve 36 by a pipe 5I.A second port 52 of valve 36 is connected to a port 53'of 4-way valve 43by a pipe 54.y A third port of valve-36 is connected to makeup tank1 bythe pipe 35.

Valve 36 comprises a central chamber .56 having arotatable valve element51 mounted `therein. A lever .60 is secured to valve element 51exteriorly of the valve casing, and is adapted tobe engaged by an arm 6|provided at the outerv end of the piston rod 62 secured to and extendingoutf Wardly from piston 63. Piston 63 operates in th cylinder 64 of amotor 65 of the extruding paratus 5. The plunger ofA platen 4 secured tothe opposite facek of piston 63 extends throughk the lower end ofvcylinder y64 and is adapted, to" f OFF ICE y l' |62, the formerengaging crosshead |34 while ther latter is positioned near the lefthand end of rod |35 and held in position by nuts |53 making threadedengagement with the left hand end of said rod. Movement of. crossheadA|34 to the right is limited by the collar 4| as is clearly apparent inFig. 4. The pressure of spring |5| may be adjusted by simply adjustingnuts |53; To place pump 2 on stroke, the pressure of spring |5| isadjusted the required amount. Spring `|5| now urges crosshead |34 to theright and moves levers |28, |28 in a clockwise direction (Fig. 2)causing guide rods |24 to move to the left, thereby placing the pump onstroke. The pressure at which the pump is to be maintained on stroke maybe predetermined by adjustment of spring |50.

It is also seen that upon manipulation of hand wheel |44, rotarymovement is imparted to sleeve |38 which in turn imparts a translationalmovement to rod |35. By this action collar |4| is brought toward or awayfrom crosshead |34, depending upon the direction of movement of Wheel|44. When the collar |4| lies in abutting relation with flange |39, asshown in Fig. 4, crosshead |34 may be urged the greatest distance byspring |50, and consequently in that position the pump may be adjustedto maximum stroke. As collar |4| is caused to move toward crosshead |44the stroke of the pump is correspondingly decreased.

As shown in Figs. l and 2, the left hand end of cylinder ||8 isconnected to pipe 39 by branch pipe |55. Accordingly, when valve member24 has been adjusted to the position A the left hand end of piston ||9`will be subjected to the system pressure. When the pressure impressedagainst piston ||9 exceeds that of spring |50, piston ||9 will move tothe right (Fig. 2), thereby rocking levers |28 in a counter-clockwisedirection against the pressure of spring |50 to bring the sliding blocksof pump 2 towardv neutral position. The pump controls are so adjusted,as will appear more fully hereinafter, that thepump will alwaysdischarge a certain amount of uid at the pressure to which spring wasoriginally sin adjusted, even when piston ||9 has actuated levers |28 totheir limiting position.

As shown in Fig. 2, the opposite endV of pump 2 has secured thereto bybolts |56 a motor |51. Motor |51 comprises a cylinder |58 having apiston |59 operating therein. A port |60 connects the right hand end(Fig. 2) of cylinder |58 with the exterior of the casing. and hascpnnected thereto one end of a pipe |6|. The other end of pipe |6| isconnected to the port |62 of a pressure valve |63. Pressure valve |63comprises a casing |64 having a plunger |65 operating therein. A secondport |66 provided near the lower end of casing |64 is connected to pipe39 by a branch pipe |61. A spring |68 extends between plunger and aspring seat |69. Spring A port |16 provided at the other end of cylin-vder |58 is connected to pipe |06 by a pipe |11. The piston rod |18 ofpiston |59 extends through a packing gland |19, secured to cylinder |58in any suitable manner, such as by bolts |80, |80.

Rod 18 also extends through a guide block |8| spaced from gland |19 bythe extensions |82, |82L of bolts |80, |80.v Nuts |83 engaging the outerside of gland |19 may urgel the latter inwardly and thereby preventleakage of oil past the piston rod. Member |8| is held in `spacedposition by the 'sliding blocks |25 of pump 2 in any suitable Nuts|81,`secured to rods |86 at the Y manner. opposite sides of crosshead|85, hold the said crosshead 1n proper position.y

The distance that crosshead may move toward pump 2 may be varied byadjusting crosshead |85 and guide member |8| toward' or away from eachother. This may be done by adjusting, respectively, the nuts |81 and |84on rods |86 and the extensions |82 of bolts |80. Thus the strokecontrols |25 of pump 2 may be adjusted from neutral position to fullstroke position, thereby permitting the pump 2 to discharge amounts offluid in proportion to the adjustments of the members just describedwhen said stroke controls are moved to their limit of adjustment in onedirection.

From the foregoing description of the structure of my improved device,the operation thereof is thought to be obvious. However, in order tocorrelate the various elements thereof a brief rsum of the operation ofthe apparatus as a whole willnow be given.

Handwheel |44 is first adjustedvthe proper amount to insure properstroking of pump 2.

Spring 46 of valve 42 is also adjusted to the proper pressure, saypounds per square inch, depending upon what pressure in the system isnecessary to insure proper operation `of valve I.

are also adjusted to permit discharge of fluid from pumps 2 and 3respectively to exhaust, to prevent abnormal pressures in the system.Crosshead |85 and guide member |8| are also so adjusted as to cause thepump 2 to discharge the proper amount of fluid when piston ||9 of motor|1 has fully actuated the stroke controls |25 to the right (Fig. 2).

Valve element 24 of operating valve 2| is now shifted to the right (Fig.l) to the A position. Fluid from pump 2 will now enter port 20 of valve2| through pipes l0 and 22. Fluid from pump 3 also will now flow to port20 of valve 2| through pipe 18, port 19 of valve 43, chamber 1|, port96.`

pipe 98, valve and pipes |0 and 22. The fluid entering port 2|)r willnow flow through central chamber 23 of valve 2i, port 31, and into pipe38. The fluid in pipe 38 will now enter the lower end of valve 42through branch pipe 4|, and when the pressure of the fiuid acting on thelower end of plunger 45 is sufficient to overcome the pressure of spring46 the said plunger will move upwardly to permit fluid to flow from saidvalve to the upper end of cylinder 64 of extruding apparatus 5 throughpipes 15 and 12. pipe 38 will' now also flow through pipe 39 and entercylinder ||8 of motor ||1 through pipe |55.

Fluid from A Piston 63 and platen 4 of extruding apparatusv will nowmove downwardly ata relatively high rate of speed since the combineddischarges of -pumps 2 and 3 now enter the upper end of cylinder 64.When arm 6| on piston rod 62 engages arm 60, valve element 51 will beshifted to the broken line position shown in Fig. 3, whereupon the fluidentering valve 36 through pipe 5| will now be discharged therefromthrough port 52 and into pipe 54, from which it enters port 53 at theright hand end of 4-way valve 43. When this occurs valve element ofvalve 43 will be urged to the left (Fig. l) causing valve head 8| todisconnect port 96 from chamber 1|, and thus permitting the discharge ofpump 3 to pass to makeup tank through pipes 18, chamber 1|, port andpipe I |O. Pump 2 will now continue to operate alone to supply fluidpressure to the upper end of cylinder 64.

When platen 4 engages the work in mold 66 this resistance to itsmovement causes the pressure in the system developed by pump 2 toincrease. This pressure, it will be remembered, is

communicated to the left inane end (Fig. 2) of piston. H9, and tends tomove the latter to the right against the pressure of spring |50. As theplaten descends, the materials in the mold 66 are compressed, causingthe air bubbles and some moisture to be eliminated therefrom. Theresistance also increases causing the pressure in the system to build upthereby urging piston H9, and consequently the stroke controls |25 ofpump 2 to move to the right until crosshead |85 engages The discharge ofpump 2 is thus member |8|.` materially reduced and platen 4 continues todescend at a correspondingly reduced speed. The pressure in the systemcontinues to increase, and when the pressure at the lower end of plunger|65 of valve |63 is sufficient to overcome the pressure of spring |68said plunger will move upwardly to uncover port |62, and thereby permitfluid from pipe 39 to enter the right hand end of cylinder |58 of motor|51. Piston |58 of motor |51 will now move to the left and assist spring|50 to pla-ce pump 2 on full stroke. It will be noted that the diameterof piston |59 is greater than that of ||9 and consequently there will bea much greater pressure tending to maintain the pump on full stroke thanthat tending to urge it toward neutral position. As a result a greaterquantity of fluid will now be discharged by pump 2, thereby causingpiston 63 and platen 4 to move downwardly at a greater rate of speed.This speed will now cause extrusion of the material through the die 68.The rate of extrusion may be controlled by manipulation of handwheel|44. Should the rate of extrusion be too great handwheel |44 may be somanipulated as to cause a reduction in the stroke of pump 2 and therebydecrease the discharge of said pump. On the other hand, if the extrusionis at a slower than the desired rate of speed the hand wheel may be somanipulated as to increase the stroke of pump 2, and thereby cause agreater discharge of the latter, and a consequent movement of platen 4at a greater rate of speed.

When the materials have been fully extruded from mold 56 the operatormoves lever 28 to position B. Fluid from pump 2 will now enter the lowerend of cylinder 64 through pipes ||l and 22, port 20 of valve 2|,chamber 23, port |03 and pipe |04. The fluid pressure in pipe |04 willnow enter the cylinder at the left hand end of valve 43 through pipe |06thereby causing the valve element 10 to be shifted to the right. Whenthis occurs fluid from pump 3 will also-fiowinto pipe 22 through pipe18, port 19, chamber 1| of valve 43, port 96, pipe 98, and valve |I. Thecombined discharges of pumps 2 and 3will cause piston 63 and platen 4 tomove upwardly at a relatively rapid rate of speed. The fluid at ltheupper end of cylinder 64 will now discharge to exhaust through pipe 12,valve 40, -pipe 38, port 31 of valve 2|, the left hand end of chamber23,

passages 3| and 30, port 33, and pipes 34 and 35.l

Fluid pressure will also now be conducted to the left hand end ofcylinder |58 of motor |51, through pipes |06 and |11, and port |16. Whenthis occurs piston |59 will be moved to the right (Fig. 2) to bringpiston |59 back to its normal position. Fluid at the right hand end ofcylinder |58 will now discharge to makeup tank 1 through port |60, pipe|6|, valve |12, pipe 39, pipe 38, port 31 of valve 2|, passages 3| and30, port 33 and pipes 34 and 35. When piston G3 approaches its upperlimit of adjustment arm 6| will engage arm 60, secured to valve element51, and upon further upward movement the parts will be restored to theposition shown in full lines in Fig. 1.. The, device is now ready foranother cycle of operation.

Itis also seen that when piston 63 moves downwardly the fluid at thelower end of cylinder 64 will discharge to makeup tank through pipes|04, the right hand end of chamber 23 of valve 2|, passages 32 and 30,port 33 and pipes 34 and35.

From the foregoing description it is seen that a highly efficient devicehas been provided which permits operation of the apparatus through apredetermined cycle. The device functions to compress the materials inthe mold until ready for extrusion and thereafter to effect extruding atthe proper pressure. The device is also so constructed as to enable theoperator to control the rate of extrusion manually, and thereby insure aproduct of the proper consistency.

While the embodiment herein shown and described is admirably adapted tofulfill the objects primarily stated, it is to be understood that theinvention is not to be limited thereto, since it may be embodied inother forms, all coming Within`the scope of the-claims which follow.

What-is claimed is:

1. In a fluid system of the class described, the combination of a pairof pumps, a fluid motor adapted to be actuated by said pumps, areversing Vvalve for controlling the operation of said fluid motor,piping connecting said pumps to said reversing valve, a shiftable valveadaptedtocone nect one of said pumps to, or disconnect it from, thesystem, a control valve for controlling the operation of said shiftablevalve in one direction, means actuated by said fluid motor for actuatingsaid control valve to different positions, control means for the otherof said pumps for controlling the stroke and pressure characteristicsthereof including resilient means for placing said pump on stroke, aservo motor adapted to operate from its normal position in unison withsaid resilient means to actuate said pump toward full stroke position, apressure actuated valve for controlling the operation of said servomotor, means controlled by the operation of said reversing valve foractuating said shiftable valve in the opposite direction, and meanscontrolled by said reversing valve for actuating said servo motor tonormal position.

2. In a iluid system of the class described, the combination of a pairof pumps, a fluid motor adapted to be actuated by said pumps, areversing valve for controlling the operation' of said fluid motor,piping connecting said pumps to said reversing Valve, a shiftable valveadapted to connect one of said pumps' to, or disconnect it from, thesystem, a control valve forcontrolling the operation of said shiftablevalve in one direction, means actuated by said uid motor for actuatingsaid control valve to different positions. control means for the otherof said pumps for controlling the stroke and pressure characteristicsthereof including resilient means for placing said pump on stroke, aservo motor operable by the pressure in the system adapted to operatefrom its normal position in unison with said resilient means to actuatesaid pump toward full stroke position, a valve actuated by the pressure'in the system for controlling the 'operation of said servo motor, meanscontrolled by the operation of said reversing valve for actuating saidshiftable valve in the opposite direction, and means controlled by saidreversing valve and operable by the pres- Y sure in the system foractuating said servo motor to normal position.

PAUL N. OBERHOLTZER.

Jan. 4, 1944. A. J..PARR|sH BORING'MAGHINE Filed Aug. s. 1940 5Sheets-Sheet l

